Short-wave tube transmitter



Feb. 18, 1930. w. SCHEPPMANN SHORT WAVE TUBE TRANSMITTER Filed Jan. 25, 1928 Patented Feb. 18, 1930 UNITED STATES WILHELM SCHEPPMANN, or BERLIN-TEMPELHOF, GERMANY SHORT-WAVE TUBE TRANSMITTER Application filed January 25, 1928, Serial No. 249,441 and in Germany January 25, 1927.

This invention relates to the generation of high-frequency electric oscillations by means of vacuum tubes and is more particularly intended for use in apparatus for short wa es.

One object of my invention is to get a large working efficiency of short wave-transmitters with the smallest possible amount of apparatus, adapted, therefore, for use with portable wireless stations. v I Another object of my invention is to en able short wave transmitting apparatus to be operated by unskilled persons.

My invention is more clearly set forth by the following detailed disclosure taken with reference to the accompanying drawings, the special features as to what I claim as novel being pointed out in the appended claims. .Of the drawings a Figure 1 shows a wiring diagram of a short -.wave transmitter as known hitherto in the art,

Figure 2 represents one form of carrying out my invention,

Figure 3 is a diagram similar to that of 25, Figure 2. c

In order to get the most favorable transmission of energy from the high frequency generator to the radiating or antenna circuit, it hasbeen customary hithertoto tune both the generator circuit and the antenna After this, the generator circuit is retuned anew which again makes necessary another retuning of the antenna c rcuit. Besides this,

care must be taken that the coupling between the generator and the antenna circuit be not too close, as, otherwlse, two coupling waves,

will be produced in the case of a separately excited transmitter or phenomena of instability will occur in the case of self excited tank circuit.

, on the other hand,as the generator is always working upon the same antenna or upon an antenna having equal working COIldllZlODS.

However, conditions change when working with short waves, where the tunlng involves greater difficulties, especiallyin thecase ofa fairly transportable and able to be adapted readily to the various conditions corresponding to their varying locations, the use of a number of ammeters and tuning means is prohibitive.

There have already become known circuit connections especially intended for short wave transmitters providing an antenna circuit devoid of tuning means (aperiodic an: tenna) and requiring only the proper tube generator circuit to be tuned to the desired operating wave length. Referring to the accompanying drawing Figure 1 shows such a circuit connection comprising a self-oscillating tube transmitter with an inductive coupling of the generator circuit with the portable stations. As such stations must be antenna circuit. According to this figure, 1

denotes the oscillating tube of thev standard three-electrode type, 2 the anode circuit tuning capacity and '3 the anode circuit self inductance, both being arranged in the Wellknown parallel relationship of a storage or The feedback of the anode circuit with the grid is efiected by a suitable tapping on the anode circuit self-inductance 3. The aperiodic or untuned antenna circuit which is fairly out of tune with the operating frequency produced in the generator circuit 2,3, is composed of an antenna 4, coupling coil 5. variably coupled to anode circuit self-inductance 3 and earth connection 6. 7 is a choke coil blocking the high frequency current against the anode current source connected at i and 8 is a blocking condenser preventing the direct current of the anode supply source from flowing into the circuit parts carrying high-frequency currents. If tube 1' is regarded as a generator whose terminals are its anode and cathode electrodes respectively and at which the produced voltage may be taken off (there may also be present a tube separately excited, for instance, a tube controlled by means of a quartz crystal) and the antenna circuit is regarded as the load or consuming circuit, energized by the generator, then, to get most favorable operatin conditions, it is necessary, on the one han to adapt the inner generator resistance to the resistance of the load (antenna) and on the other hand to tune the entire load circuit to the frequency supplied by the generator. With a connection according to Figure. 1 the arrangement is such that first the tuning of the generator circuit is carried out and. afterwards the adaptation of the generaitor circuit 2,3 to the antenna load circuit 4, 5,. 6 (transformation by coupling 3-5) is adjusted. Such a connection in practice has proven to possess great disadvantages when compared with a circuit connection forming the subject matter of the present invention and having as characteristic features adaptation and tuning reversed as compared with I the known circuit in accordance to Figure 1, i; e., that of carrying out the adaptation ofthe generator to the load circuit and then bers refer to similar elements as in the case of Figure 1. The tube 1 is assumed to be an amplifier tube excited by an exciter coupled'to itsgrid electrode and having an aperiodic 0r untuned anode circuit containing only a self inductance 1O variably coupled with self inductance 11 of the tuned tank circuit 11,12 inserted in series with an antenna 4 and.

earth connection 6. 12 is the tuning capacity of the antenna tank circuit. 9 is an ammeter for adjusting the transmitter to maximum antenna output. The exciter comprises a tube 19 working in a self excitation circuit, its anode being connected across an inductance 20 with its grid. The heating filament is tapped into the inductance 20 to which a capacity 21 is connected in parallel. The oscillations are imposed upon the grid circuit of tube 1 across an inductance 22, V

Referring to Figure 3 of the drawings a capacitative coupling between generator and antenna circuit is shown instead of an inductive or magnetic coupling as shown by the embodiment of my invention represented by Figure 2. 1 again denotes the tube which is assumed to be separately excited, 1'3 is a capacity in the aperiodic anode circuit, 16 is a variable coupling capacity and 14' and 15 are two fixed coupling condensers for coupling the anode circuit to the tuned antenna circuit comprising antenna 6, loading coil 18, tuning condenser 17 and earth connection 6.

7 is a choke coil identical with the choke coil 7 according to Figure 2. As may readily be seen, for operation only one single tuning means is to be adjusted (antenna circuit tuning condenser 12 in case of Figure 2 or coupling condenser 16 in case of Figure 3) and the ammeter 9 to be watched for maximum reading. By varying the degree of coupling betweenthe generator and load (antenna) circuit, in all cases, an adaptation of the antenna resistance to the generator resistance may be adjusted whereby the most favorable energy transmission efiiciency is readily secured. In the case of Figure 2.this may be carried out simply by varying the degree of coupling between the coupling coils 10 and 11 and in case of Figure 3 by varying the coupling condenser 16, and in this latter case it is preferableto mechanically unite both condensers 16 and 17 in such a waythat the tuning conditions of the antenna circuit when varying condenser 3 be maintained; This latter mode ofcapacitative coupling especially has proven to be of great advantage with short waves. The tube 1 in Fig. 3 may be energized by an emitter as in the construction shown in Fig. 2. V V V The advantages of a connection in accordance with the present invention shown by way of examples by Figures 2 and 3 @11 sis ting essentially in an aperiodic generator circuit and a tuned antenna circuit coupled therewith, especially lie in a better trans mission efficiency of the energy from the generator circuit to the load circuit and in improved uniformity and constancy of the waves radiated, as in this case, in contrast to the known connection of Figure 1,t1'1'e antenna circuit because of its tuning to the operating tenna circuit are well known, which also are essentially due, on the one hand, to the favorable adaptation of the generator, which in this case is represented by the antennaitself,

to the load or consuming circuit, e. g., the grid circuit of a receiving tube energized by the antenna circuit, on the other hand, to

improved selectivity. Thus, Figure 1 represent such a well known receiving circuit connection if one considers the antenna to absorb wireless waves fromanother station instead of radiating itself. When changing, therefore, such a circuit from a receiving circuit into a transmitting circuit, a circuit arrangement will be obtained as shown by Figures 2 and 3 in accordance with the theoretical considerations underlying the present invention wherein the antenna has changed its function as generator to that of a consumer or a load.

What I claim to be secured Letters Patent of the United States is:

1. An apparatus for the generation of short electric waves, comprising, in combination, a three-electrode, vacuum tube, an aperiodic tube working circuit, and an antenna circuit tuned to the frequency of the waves to be radiated and variably coupled with said aperiodic circuit. o

2. An apparatus for the generation of short electric waves, comprising, in combination, a three-electrode vacuum tube, a control circuit for said tube, a separate control oscillator, for energizing said control circuit, an aperiodic Working circuit for said tube, and an antenna circuit tuned to the frequency of the oscillations supplied by said control oscillator and variably coupled with said aperiodic working circuit.

3. An apparatus for the generation of short electric waves, comprising, in combination, a three electrode vacuum tube hav- 26 ing incandescent cathode, anode and controlling grid electrodes, a control oscillator controlling the grid electrode of said tube, an aperiodic anode circuit for said tube including a self-inductance coil, and an antenna circuit including in series an oscillating circuit tuned to the wave length of said control oscillator and variably coupled with said self-inductance coil. a

4. An apparatus for the generation of 3 short electric waves comprising, in combination, a three electrode vacuum tube, an energizing input circuit connected to the grid electrode of the tube, an aperiodic output circuit connected to the plate electrode of the 85 tube, and an antenna-ground radiator including a tuned local oscillation circuit having a variable coupling with the output circuit.

5. An apparatus for the generation of short 4Q electric Waves comprising, in combination, a three electrode vacuum tube, an energizing input circuit connected to the grid electrode of the tube, an aperiodic output circuit connected to the plate electrode of the tube, and

an antenna-ground radiator including a closed oscillation circuit provided with tuning means and having a variable coupling with the output circuit. 7

6. An apparatus for the generation of 5 short electric Waves comprising, in combination, a three electrode vacuum tube, an energizing input circuit connected to the grid electrode of the tube, an aperiodic output circuit connected to the plate electrode of the tube and including the primary of a coupling transformer, and an antenna-ground radiator including a closed local oscillation circuit having in series with antenna and ground and in parallel with each other a tuning concc denser and the secondary of said transformer, the primary and secondary of the transformer being adjustable to vary the coupling.-

In testimony whereof I have aflixed my signature. e5 WILHELM SCHEPPMANN. 

